CN111697940A

CN111697940A - Low-loss double-frequency negative group delay circuit and design method

Info

Publication number: CN111697940A
Application number: CN202010455343.2A
Authority: CN
Inventors: 万发雨; 吴丽丽; 李宁东; 布莱斯
Original assignee: Nanjing University of Information Science and Technology
Current assignee: Nanjing University of Information Science and Technology
Priority date: 2020-05-26
Filing date: 2020-05-26
Publication date: 2020-09-22
Anticipated expiration: 2040-05-26
Also published as: CN111697940B

Abstract

The invention discloses a low-loss double-frequency negative group delay circuit and a design method thereof. The center frequency points realized by the structure are respectively 1.9GHz and 2.55GHz, the actually measured reflection coefficient S11 is lower than-10 dB, and the loss S21 is better than-3 dB. The invention can generate double frequency points and keep low attenuation, realizes the miniaturization of a negative group delay circuit, reduces the loss and reflection of the circuit, improves the group delay bandwidth and delay, and can be used in an antenna array to eliminate beam tilt.

Description

Low-loss double-frequency negative group delay circuit and design method

Technical Field

The invention belongs to the field of microwave engineering, and particularly relates to a low-loss double-frequency negative group delay circuit and a design method thereof.

Background

Negative Group Delay (NGD) networks have attracted considerable attention in recent years due to their practical and potential use in various microwave systems. In phased array antenna systems, they are used to shorten or eliminate the delay line, improve the efficiency of feed forward linear amplifiers, and minimize beam squint of the array antenna. It is worth noting that most NGD microwave circuits are built on lumped RLC networks, and there are problems of parasitic parametric effects of lumped elements at radio and microwave frequencies.

Disclosure of Invention

The purpose of the invention is as follows: the first purpose of the invention is to provide a low-loss double-frequency negative group delay circuit which can reduce the loss and reflection of an NGD circuit, improve the group delay bandwidth and delay and realize multiple frequency points; the second objective of the present invention is to provide a low-loss double-frequency negative group delay circuit design method for optimizing the circuit.

The technical scheme is as follows: the microstrip antenna comprises a coupling microstrip line and a plurality of microstrip transmission lines, wherein a port 1 of the coupling microstrip line is an input port, a port 2 of the coupling microstrip line is an output port, a first microstrip transmission line is connected between a port 3 and a port 4 of the coupling microstrip line, a second microstrip transmission line is connected between a port 5 and a port 6 of the coupling microstrip line, and a third microstrip transmission line is connected between a port 7 and a port 8 of the coupling microstrip line.

The length of the first microstrip transmission line is smaller than that of the second microstrip transmission line, and the second microstrip transmission line and the third microstrip transmission line are the same in size.

The second microstrip transmission line and the third microstrip transmission line are semicircular in structure.

The circuit structure of the negative group delay circuit is a symmetrical structure.

The negative group delay circuit adopts FR4 board, the thickness of the board is 1.6mm, the size is 61mm multiplied by 98mm, the dielectric constant is 4.4, the tangent loss angle is 0.02, and the copper thickness is 0.035 mm.

The invention also comprises a design method of the low-loss double-frequency negative group delay circuit, which comprises the following steps:

(1) simulating and designing and optimizing various parameters of the coupling microstrip line and the plurality of microstrip transmission lines in the negative group delay circuit by using ADS simulation software to obtain the size of each electromagnetic parameter of the negative group delay circuit;

(2) and carrying out real object processing according to the optimized negative group delay circuit.

In the step (1), the negative group delay circuit realizes double frequency in the L frequency band and the S frequency band; when the central frequency is 1.9GHz, the measured group delay of the circuit is about-0.95 ns, and electricityMeasured loss S of road₂₁About-2.05 dB, the measured reflection S of the circuit₁₁Is-13.4 dB; when the central frequency is 2.55GHz, the actual group delay of the circuit is about-1.1 ns, and the actual loss S of the circuit₂₁About-2.4 dB, the measured reflection S of the circuit₁₁Is-15.2 dB.

Has the advantages that: compared with the prior art, the invention has the beneficial effects that: (1) the miniaturization of the NGD circuit is realized; (2) the loss and reflection of the circuit are reduced, the group delay bandwidth and the delay are improved, and the multi-frequency point negative group delay circuit is realized; (3) the double-frequency point can be generated, and low attenuation can be kept; (4) the problem of beam tilt in antenna arrays can be eliminated.

Drawings

FIG. 1 is a schematic diagram of a negative group delay circuit according to the present invention;

FIG. 2 is a circuit schematic of the negative group delay circuit of the present invention;

FIG. 3 is a circuit diagram of a negative group delay circuit according to the present invention;

FIG. 4 is a diagram illustrating a simulation result of the group delay of the negative group delay circuit according to the present invention;

FIG. 5 is S of the design method of negative group delay circuit according to the present invention₂₁A simulation result schematic diagram;

FIG. 6 is S of the negative group delay circuit design method of the present invention₁₁And (5) a simulation result schematic diagram.

Detailed Description

The invention is described in further detail below with reference to specific embodiments and the attached drawings.

As shown in fig. 1 to fig. 3, the microstrip transmission line structure of the present invention includes two identical coupling microstrip lines CL and a plurality of microstrip transmission lines TL, where a port 1 of the coupling microstrip line CL is an input port, a port 2 of the coupling microstrip line CL is an output port, a first microstrip transmission line TL1 is connected between a port 3 and a port 4 of the coupling microstrip line CL, a second microstrip transmission line TL2 is connected between a port 5 and a port 6 of the coupling microstrip line, and a third microstrip transmission line TL3 is connected between a port 7 and a port 8 of the coupling microstrip line. The coupling microstrip line CL is connected between the port 1 and the port 3, the coupling microstrip line CL is also connected between the port 4 and the port 2, and the double-frequency negative group delay circuit can be realized through the circuit structure. In this embodiment, the length of the first microstrip transmission line is smaller than that of the second microstrip transmission line, and the second microstrip transmission line and the third microstrip transmission line have the same size. The structure of the second microstrip transmission line and the structure of the third microstrip transmission line are both semicircular.

As shown in fig. 4, the circuit structure of the negative group delay circuit is a symmetric structure; the negative group delay circuit adopts FR4 board with thickness of 1.6mm, size of 61mm × 98mm, dielectric constant of 4.4, tangent loss angle of 0.02 and copper thickness of 0.035 mm.

As shown in fig. 1 and 4, the circuit structure of the negative group delay circuit is a symmetric structure, and the optimization result of the ADS simulation software on the NGD circuit size is shown in the following table:

TABLE 1 NGD Circuit fundamental parameter dimensions

As shown in fig. 4 to 6, the negative group delay circuit of the present invention is a dual-frequency negative group delay circuit, and the negative group delay circuit realizes dual-frequency in the L-band and the S-band; when the central frequency is 1.9GHz, the actually measured group delay of the circuit is about-0.95 ns, and the actually measured loss S of the circuit₂₁About-2.05 dB, the measured reflection S of the circuit₁₁Is-13.4 dB; when the central frequency is 2.55GHz, the actual measurement group delay of the circuit is about-1.1 ns, and the actual measurement loss S of the circuit₂₁About-2.4 dB, the measured reflection S of the circuit₁₁Is-15.2 dB. From the simulation and the actual mapping, the second center frequency of the negative group delay circuit is simulatedThere is a true to measured deviation that can be related to machining errors of the sheet material and to deviations of the dielectric constant of the sheet material from the nominal value.

Claims

1. A low-loss double-frequency negative group delay circuit is characterized in that: the microstrip line coupling structure comprises a coupling microstrip line and a plurality of microstrip transmission lines, wherein a port 1 of the coupling microstrip line is an input port, a port 2 of the coupling microstrip line is an output port, a first microstrip transmission line is connected between a port 3 and a port 4 of the coupling microstrip line, a second microstrip transmission line is connected between a port 5 and a port 6 of the coupling microstrip line, and a third microstrip transmission line is connected between a port 7 and a port 8 of the coupling microstrip line.

2. The low loss, dual frequency, negative group delay circuit of claim 1, wherein: the length of the first microstrip transmission line is smaller than that of the second microstrip transmission line, and the second microstrip transmission line and the third microstrip transmission line are the same in size.

3. The low loss, dual frequency, negative group delay circuit of claim 1, wherein: the second microstrip transmission line and the third microstrip transmission line are semicircular in structure.

4. The low loss, dual frequency, negative group delay circuit of claim 1, wherein: the circuit structure of the negative group delay circuit is a symmetrical structure.

5. The low loss, dual frequency, negative group delay circuit of claim 1, wherein: the negative group delay circuit adopts FR4 board, the thickness of the board is 1.6mm, the size is 61mm multiplied by 98mm, the dielectric constant is 4.4, the tangent loss angle is 0.02, and the copper thickness is 0.035 mm.

6. A method for designing a low loss dual frequency negative group delay circuit as claimed in claim 1, comprising the steps of:

7. The design method of the low-loss dual-band negative group delay circuit of claim 6, wherein: in the step (1), the negative group delay circuit realizes double frequency in the L frequency band and the S frequency band; when the central frequency is 1.9GHz, the actually measured group delay of the circuit is about-0.95 ns, and the actually measured loss S of the circuit₂₁About-2.05 dB, the measured reflection S of the circuit₁₁Is-13.4 dB; when the central frequency is 2.55GHz, the actually measured group delay of the circuit is about-1.1 ns, and the actually measured loss S of the circuit₂₁About-2.4 dB, the measured reflection S of the circuit₁₁Is-15.2 dB.